2hash simultaneously performs a md5 and a sha1 checksum on file(s).
If you want two checksums for additionally integrity checking, you previously
had to run md5sum and sha1sum serially causing the integrity checks to
take 100% longer than running a single check alone. 2hash runs both hashes
in parallel, only having to read the file once. It allows you to
get both hash values with only about an 8% time increase over md5 alone,
and only about a 2% time increase over sha1 alone. It runs about 90%
quicker than using both md5 and sha1 one after the other...